1. Field of Invention
The present invention relates to a gas distribution system for a vacuum processing system, and more particularly to a gas distribution system for introducing a process gas in a vacuum processing system.
2. Description of Related Art
During semiconductor processing, a (dry) plasma etch process can be utilized to remove or etch material along fine lines or within vias or contacts patterned on a silicon substrate. The plasma etch process generally involves positioning a semiconductor substrate with an overlying patterned, protective mask layer, for example a photoresist layer, in a processing chamber.
Once the substrate is positioned within the chamber, an ionizable, dissociative gas mixture is introduced within the chamber at a pre-specified flow rate, while a vacuum pump is throttled to achieve an ambient process pressure. Thereafter, a plasma is formed when a fraction of the gas species present are ionized by electrons heated via the transfer of radio frequency (RF) power either inductively or capacitively, or microwave power using, for example, electron cyclotron resonance (ECR). Moreover, the heated electrons serve to dissociate some species of the ambient gas species and create reactant specie(s) suitable for the exposed surface etch chemistry.
Once the plasma is formed, selected surfaces of the substrate are etched by the plasma. The process is adjusted to achieve appropriate conditions, including an appropriate concentration of desirable reactant and ion populations to etch various features (e.g., trenches, vias, contacts, etc.) in the selected regions of the substrate. Such substrate materials where etching is required include silicon dioxide (SiO2), low dielectric constant (i.e., low-k) dielectric materials, poly-silicon, and silicon nitride.
While the process gas chemistry is selected to facilitate the etch process at the substrate surface, it poses a harsh environment for the interior surfaces of the processing chamber. The process gas can include corrosive gases that may be detrimental to components of the processing chamber, and may lead to the contamination of the substrate, hence reducing yield during the fabrication of integrated circuits (ICs)